With a query such as:

select e1, (select e1 from (select t1.e1 from pm1.g1 as t1) as t2 where t2.e1 = t1.e1) from pm2.g1 as t1

The correlated reference to t1.e1 will get evaulated as if it were a local value from pm1.g1 as t1 instead. This is because the evaluator doesn't immediately look for the context value, but rather calls to internalEvaluate.